Hydraulic speed press



April 12, 1938. R. TYLER HYDRAULIC SPEED PRESS Filed May 3, 1937 2 Sheets-Sheet l INVENTOR. HANSDM TYLER BY 1 A I I r i R. TYLER April 12, 1938;,

HYDRAULI 0 SPEED PRES S I 2 Sheets-Sheet 2 Filed May 3, 1957 JNVENTOR. HANsuM TYLER BY [ATTORNEY Patented Apr. 12, 1938 [TED Oilgear Company,

ration of Wisconsin Milwaukee, Wis, a corpo- Application May 3, 1937, Serial No. 140,i'73 9 Claims. (Cl. 60-52) This invention relates to hydraulic presses of thetype having a ram arranged in a stationary cylinder, a reciprocating hydraulic motor for advancing and'retracting the ram toward and from the work at high speed, a reversible pump for supplying liquid to the motor to operate the same, a. surge tank for supplying liquid to the ram cylinder when the ram is being advanced by the motor and for receiving liquid ejected from the ram cylinder when the ram is being retracted by the motor, and a surge valve for controlling communication between the ram cylinder and the surge tank and adapted when the motor stalls at the end of the advance movement of the ram to'close the ram cylinder to the surge tank and open it to the pump to enable the pump to supply liquid to the ram cylinder and thereby cause the ram to exert a high pressing force upon the work. "The surge valve is shifted in response to variation in the pressure differential between the two sides of the hydraulic circuit which connects the pump to .the press cylinders.

The liquid delivered by the pump to the ram cylinder compresses the liquid therein, and. the pressure in the ram cylinder acts upon the surge valve and holds it in a position to block communioation between'the ram cylinder and the surge tank with the result that, when the pump is reversed, the ram cannot be retracted until the pump has pumped sufficient liquid from the ram cylinder to reduce the pressure therein enough to permit the surge valve to shift, thereby causing a delay equal to a large percentage of the time required .for a complete cycle of operation. 3 The present invention has as an object to provide means for relieving the pressure in the ram cylinder in response to reversal of the pump.

In the presses of the downward pressure type, the combined weight of the ram, the piston and 40 piston rod of the motor, the platen and the die carried bythe platen is often so great that the ram will fall as soon as the pump is adjusted to start a down stroke, thereby causing a heavy impact against the work and creating a partial 45 vacuum in the upper end of the motor cylinder. Another object of the present invention is to provide a hydraulic speed press in which the outflow from the motor is metered by the pump to thereby prevent the ram from descending at a rate greater than the rate determined by the adjustment of the pump.

Other objects and advanages' will appear from the following description of the hydraulic press shown in the accompanying drawings in which 65 the views are as follows:

Fig. 1 is a diagrammatic view illustrating the hydraulic circuit of the press and showing the several parts in the positions occupied when the press is idle and the ram is at the top of its stroke.

Fig. 2 is a detail view of the surge valve and 5 shows it in the position occupied when the press is acting upon the work.

Fig. 3 is a detail view showing an automatic valve in a position different from that shown in Fi 1. I

- 1 Fig. 4 is a detail viewshowing the pump control valve on a scale larger than that shown in Fig. 1

and with the valve in the position occupied when the pump is at zero stroke.

Fig. 5 is a sectionalplan view taken on the line 5-5 of Fig. 4 showing the valve in elevation.

Fig. 6 is a sectional view taken on the line 6-6 of Fig. 4.

Fig. '7 is a view similar to Fig. 6 but showing the control valve shifted to a position to cause the pump to deliver liquid at its full volumetric rate in a direction to raise the ram of the press.

The press chosen for illustration includes a movable press head or platen l which is adapted to be moved toward and from a stationary press head 2 by tworeciprocating hydraulic motors each of which includes a piston 3 fitted in a stationary cylinder 4 and connected to platen I by a piston rod 5. In order that platen I may exert a pressing force against head 2 or upon any work or other object placed therebetween, it is connected to a large diameter ram 6 which is fitted in a stationary ram cylinder 1.

When motive liquid-is supplied to the upper ends of cylinders l, pistons 3 will move ram 6 downward and cause it to draw liquid into the upper end of cylinder 1 from a surge tank 8 and, when motive liquid is supplied to the lower ends of cylinders 4, pistons '3 will move ram 6 upward and cause it to eject liquid from cylin- "40 der 1 into surge tank 8.

Cylinder I is connected to the lower part of surge tank 8 through a channel 9 and a surge valve l0 which has an axial bore ll formed in its casing and communicating at its right end with channel 9 and communicating intermediate its ends with a channel l2 which extends through the side wall of the surge valve casing and through the upper end of the ram cylinder.

' Communication between channel 9 and chan-' nel I2 is controlled by a valve member l5 which is closely fitted in bore II and provided with an axial bore l6 and a counterbore 11.. c The left end of bore II is closed by a cap. l8 having fixed to the inner face thereof a valve core l9 which is provided at its inner end with a large stationary piston 20 and provided intermediate its ends with a small stationary piston 2|. Piston 20 is closely fitted in counterbore l1 and piston 2| is closely fitted in bore 6.

When valve member I5 is moved to the posi-. tion shown in Fig. 1, it opens communication between channel 9 and channel l2 and closes communication between channel l2- and a port 22 which is formed in the .wall of bore H and communicates with an external channel 23 through which pressure liquid may be supplied to ram cylinder 1. When valve member I5 is moved to the position shown in Fig. 2, it closes communication between channel 9 and channel l2 and opens communication between channel l2 and port 22, communication being established by means of an annular groove 24 which is formed in the outer peripheral surface of valve member l5 and of sufllcient width to remain in communication with port 22 when valve member I5 is shifted from one to the other of its positions.

Valve member I5 is adapted to be moved to the position shown in Fig. 1 by the pressure of liquid in counterbore acting upon a shoulder 25 which is formed at the junction of bore l6 and counterbore I'l. Liquid is supplied to counterbore I! through a duct 26 which is formed in valve core l9 and extends through cap I8 into communication with an external channel 21. Valve member- I5 is adapted to be moved to the position shown in Fig. 2 by liquid supplied through a channel 28 to the left end of bore II and acting upon the left end of valve member l5.

Liquid for operating the press is supplied by a power driven pump 30 which has been shown as being of the rolling piston type fully illustrated and described in Patent No. 2,074,068. It is deemed suflicient to state herein that the pump has its pistons and cylinders arranged in a rotatable cylinder barrel 3| which'is arranged inside a thrust member or slide block 32 having an inner annular reaction surface 33 to engage the outer ends of the pump pistons.

When slide block 32 is in its central or neutral position so that the axis of reaction surface 33 coincides with the axis of cylinder barrel 3| as shown in Fig. 1, the pump is at zero stroke and no liquid will be delivered thereby. When slide block 32 is shifted in one direction or the other from its neutral position and cylinder barrel 3| is rotated, the pump will deliver liquid in a di-' rection and at a rate dependent upon the direction and distance slide block 32 is shifted from its neutral position.

As shown, cylinder barrel 3| is adapted to be rotated in the direction of the arrow so that, when slide block 32 is shifted toward the. right from its neutral position, the pump. will deliver liquid through a channel 34 to the upper ends of both cylinders 4 and have liquid returned to it from the lower ends of both cylinders 4 through a channel 35 and, when slide block 32 is shifted toward the left from its neutral position, the pump will deliver liquid through channel 35 to the lower ends of both cylinders 4 and have liquid returned to it from the upper ends of both cylinders 4 through channel 34.

In order that pump 30 may also deliver liquid to ram cylinder 1, and inorder that surge valve l0 may be operated automatically, channel 23 is connected to channel 34 intermediate the ends thereof, channel 21 is connected to channel 35 intermediate the ends thereof, channel 23 is connected at a point intermediate its endsto chan nel 28 through a resistance valve 36 which is adjusted to open at a predetermined high pressure, and channel 28 is connected to channel 23 through a check valve 31 which permits liquid to flow freely from channel 28 into channel 23 but prevents it from flowing in the opposite direction.

Slide block 32 is continuously urged toward the left by liquid pressure'in a stationary cylinder 38 acting upon a piston 39 which is fitted in cylinder 38 and connected to slide block 32. Liquid for operating piston 39 is supplied by a gear pump 40 which is ordinarily arranged in the same casing as pump 30 and driven in unison therewith as shown in the patent, referred to above. Gear pump 40 draws liquid from a reservoir 4| and discharges it into a low pressure supply channel 42 which is connected to cylinder 38. Liquid discharged'by gear pump 40 in excess of requirements is exhausted through relief valves which will be presently described and which enable gear pump 40 to maintain a constant low pressure in channel 42 and in cylinder 38.

Slide block 32 is adapted to be moved toward the right by gear pump pressure acting upon a piston 43 which is fitted in a stationary cylinder 44 and engages slide block 32. The delivery of liquid to cylinder 44 is controlled by a rotary follow-up valve 45 which is journaled in coaxial bores 46 and 41 formed, respectively, in piston 43 and in the end wall or head 48 of cylinder 44 as best shown in Figs. 4and 5.

Valve 45 has a duct 52 formed therein with its outer end in constant communication with an annular port 53 which is formed in the wall of bore 41 and connected by a channel 54 to channel 42. The inner end of duct 52 opens into a spiral groove 55 which is formed in the peripheral surface of valve 45 and normally closed by the wall of bore 46. The arrangement is such that gear pump pressure prevails in groove 55 at all times. A second spiral groove 56 is formed in the peripheral surface of valve 45 a short distance from groove 55 and opens into the right end of bore 46 from which a drain channel 51 extends through the hub of piston 43.

Grooves 55 and 56 are normally arranged upon opposite sides of a port 58 which extends through the hub of piston 43 into communication with the interior of cylinder 44 and is of a width equal to the distance between grooves 55 and 56 so that rotation of valve 45 in one direction or the other will open one or the other of grooves 55 and 56 to port 58. Valve 45 is adapted to be rotated by means of a lever 59 which is fixed upon the outer end thereof and has rotary movement through a given angular distance, for instance, degrees, from the central or neutral position shown in Fig. 6, the movement of lever 59 in each direction being ordinarily limited by stops not shown.

Wheh lever 59 is moved toward the right or in a clockwise direction in respect to Fig. 6, groove will opento port 58 and permit liquid from gear pump 40 to fiow through channels 42 and 54, port' 53, duct 52, groove 55 and port 58 into cylinder 44. The liquid entering cylinder 44 will move piston 43 and slide block 32 toward the right for the reason that piston 43 has a considerably greater pressure area than piston 39 which is also subjected to gear pump pressure.

Piston 43 will start to move as soon as groove 55 opens to port 58 and it will continue to move as long as valve 45 is rotated. As soon as rotation of valve 45 ceases, port 58 will move out of communication with groove 55 and movement of piston 43 and slide block 32 will cease.

When lever 55 is' movedtoward the left-or in a counterclockwise direction in respect to Fig. 6, groove 56 will open to port 58 and permit liquid to escape from cylinder 44 through port 58 and groove 56 into the open to drain through channel 51, thereby'per mitting the gear pump liquid acting upon piston 38 to move it and slide block 32 toward the left.

Piston 38'will start to move slide block 32 and piston 43 toward the left as soon as groove 56 opens to port 58 and it will continue to move as long as valve 45 is rotated. As soon as iotation of valve 45 ceases, port 58 will move out'of communication with groove 56 and trap-the remaining liquid in cylinder 44, thereby stopping further movement ofslide block 32 andholding it in adjusted position. Slide block 32 may thus be moved in one direction or the other by swinging lever 58 in one direction or the other, and the distance through which slide block 32 is moved is dependent upon the angular distancethrough which lever 58 is moved. y

In order to supply pump 38 with the volume of liquid required by it in excess of the volume returned to it during operation of motors 3-4 in one direction, and in order to permit exhaust of the volume of liquid discharged by motors 3-4 in excess of the volume required by pump 38 during operation of .motors 3-4 in the opposite direction, channels 34 and 35 are connected, respectively, by channels 62 and 63 to two ports 64 and 65 which are formed in the wall of a valve cham; ber 66 intermediate the ends and center ther eof.

Chamber 66 has arranged therein an automatic valve 61 having pistons 68 and 69 arranged upon its ends and closely fitted in chamber 66 to control ports 64 and 65 respectively Chamber 66 communicates at its extreme right end with channel 62 through a. channel 18, at its extreme left end with channel 63 through a channel II, and at a point intermediate the ports 64 and 65 with a supply chamber 12.

The arrangement is such that, when the pressure in channel 62is higher than the pressure in, channel 63, liquid will flow from channel 62 through channel 18 to the right end of chamber 66 and move valve 61 toward the left to the position shown in Fig. 3 and, when the pressure in channel 63 is higher than the pressure in channel 62, liquid will flow from channel 63 through channel II to the left end of chamber 66 and move valve 61 toward the right to the position shown in Fig. 1.

The liquid returned from the circuit to pump 38 in excess of its requirements is exhausted from supply chamber 12 through a channel I3 and a low pressure resistance valve 14 which discharges into reservoir II and is adjusted to open at a low pressure, for instance, at 60# per square inch.

The liquid required by pump 38 in excess of the volume returned to it from the circuit is ordinarily supplied by gear pump 48. To this end, chamber I2 is connected to supply channel 42 through a channel 15 and a low pressure resistance valve 16 which is adjusted to open at a low pressure. for

reservoir 4| through a suction channel I! and a right end .of bore 46 which is v angular distance 'in press. form no part of the present invention, the same check valve 18 in order that pump 38 may be employed in circuits in which the volumetric capacity of gear pump 48 would be insufiicient to make up the diiference between the volume required by pump 38 and the volume returned to it from the circuit. Check valve "I8permits liquid to be drawn into chamber 12 through channel 11 but prevents liquid from escaping from chamber 12 into channel 11.

In order that the press may be promptly reversed at the end of a pressing operation, means are provided for relieving the pressure in ram cylinder 1 in response to reversal of pump 38. To this end, channel 34 is connected through a channel 8|, athrottl'e valve 82 and a channel 83 to a channel 84 (Fig. 6) which is. formedin end head 48 and adapted to be connected through valve 45 to a channel 85 (Fig. 1) which has one of its ends in communication with bore '41 and its other end connected to channel 15 intermediate the ends thereof.

metrically opposite points so that the pressure prevailing in channel 84 may act upon opposite sides-of valve 45 to hy'drostatically balance the same. Valve 45 has formed therein two intersecting radial passages 86 and 81 which are adapted to register, respectively, with channels 84 and 85 when valve 45 is rotated through a predetermined a counterclockwise direction from its neutral position shown in Fig. 6 to there- ,by cause slide block 32 to be moved toward the left so that pump 38 will deliver liquid through channel 35 to the lower ends of cylinders 4 to raise ram 1 as previously explained.

The reason that channels 86 and 8'! are'not opened to channels 84 and 85 until after valve 45 has been rotated through a predetermined angular distance, for instance through 15, in a counterclockwise direction from its neutral position is to enable pump 38 to deliver sumcient liquid to the lower ends ofcylinders 4 to support platen I and the parts movable therewith should they tend to descend dueto leakage when the press is idle.

Operation The press is provided with a suitable control so that pump 38 may be reversed manually, or in response to the creation of a predetermined high pressure, or in response to platen I reach.- ing a predetermined point in its travel, depending upon the operation to be performed by the Since such controls are wellknown and have not been illustrated.- It is to be understood however that the press should be provided with suitable means for moving lever 59 to its neutral position in response to platen I approaching the upper limit of its movement and for causing lever 58 to move in a counterclockwise direction in response to platen I moving downward from its upper position so that, if platen I should descend due to leakage when the press is idle, pump 38 would be caused to deliver liquid to the lower ends of cylinders 4 to hold platen I in its upper position, as is customary in presses of this type.'

Assuming that the several parts are in the positions shown in Fig. 1 and that pumps 38 and 48 are being driven, the press will operate as follows:

Pump 38 will be at zero stroke and no liquid will be delivered thereby unless platen I tends to descend. Pump 48 will be discharging through channel 42, resistance valve 16, channel 15,.

chamber 12, channel 13 and resistance valve 14 so that it will be maintaining in chamber 12 a pressure equal to the resistance of valve 14.

and maintaining in cylinder 38 a pressure equal to the combined resistances of valves 14 and 16.

The weight of platen I and the parts movable therewith will create pressure in the lower ends of cylinders 4, and this pressure will extend through channels 35, 63 and H to the left end of valve chamber 66 and hold valve 61 in the position shown in Fig. 1 in which position piston 69 blocks port 65, thereby trapping liquid in the lower ends of cylinders 4 and preventing platen I from descending.

When lever 59 is swung in a clockwise direction in respect to Fig. 6, groove 55 will open to port 58 and permit liquid from gear pump to enter cylinder 44 and move slide -block 32 toward the right, thereby causing pump 38 to draw liquid from channel 35 and deliver it into channel 34. I

When pump 38 first starts to deliver liquid, channel 63 is blocked by piston 69 and channel 34 is open to supply chamber 12 through channel 62 and valve chamber 66 so that, for an in-. stant, pump 38 cannot increase the pressure in channel 34 above the pressure required to open resistance valve 14. However, the liquid drawn by pump 30 from channel 35 almost instantly lowers the pressure therein and consequently lowers the pressure in channels 63 and H and in the left end of valve chamber 66..and thereby permits the pressure prevailingin the right end of valve chamber -66 to shift valve 61 from the position shown in Fig. l to the position shown in Fig. 3.

Then the liquid discharged by pump 30 will flow through channel 34 to the upper ends of cylinders 4 and cause pistons 3 to move downward and expel liquid from cylinders 4 through channel 35 to the intake of pump 30. Due to the displacement of piston rods 5, the volume of liquid'discharged from the rod ends of cylinders 4 is less than the volume supplied by pump 38 to the head ends of cylinders 4, and this deficiency is made up by gear pump 40 which delivers liquid through channel 42, resistance valve 16, channel 15, supply chamber12,'valve chamber 66 and channels 63 and 35 to the intake of pump 38.

I Pistons 3 will move platen I and ram 6 down- .ward, and liquid will flow from surge tank 8 through channel 9, bore II and channel I2 to ram cylinder 1'and keep it filled.

If the weight of platen I and the parts movable therewith is gifeat enough to cause the "same to fall, that is to descendby gravity at a rate greater than the rate determined by the displacement of pump 38, pistons 3 will tend to draw liquid into the upper ends. of cylinders 4 faster than liquid would be supplied thereto by pump 30,'thereby causing the pressure in chan- 'pump 30 which would meter the outflow from cylinders 4 and prevent platen I from descending at a rate greater than the rate determined by the displacement of pump 30. As soon as valve 61 is shifted, gear pump 48 would deliver liquid through channel 42, resistance valve 16,

channel 15, chambers 12 and 66 and channels 62 and 34 to the upper ends of cylinders 4 to make up the deficiency of liquid therein.

When platen I is descending by gravity and further downward movement thereof is arrested as by platen I or a die carried thereby engaging a piece of work, the-pressure in channels 35 and 63 and in the left end of valve chamber 66 will drop .to zero as soon as downward movement of platen I 'ceases. Then the pressure prevailing in the right end of valve chamber 66 will shift valve. 61 to the position shown in Fig. 3 and thereby enable pump 38 to increase-the pressure in channel 34. .When platen I is being moved downward by liquid supplied by pump 30 to the sition shown in Fig. 3 so that the pressure in channel 34 increases in response to further downward movement of platen I being resisted by a piece of work or other object placed between platen I and stationary head 2.

The resistance to further downward movement of'platen I causes the liquid delivered by pump 30 into channel 34 to increase the pressure therein until it is high enough to open resistance valve 36 and then liquid will flow therethrough and through channel 28 into the left end of bore II and shift valve member I5 from the position shown in Fi 1 to the position shown in Fig. 2, thereby closing ram cylinder 1 to tank 8 and opening it to channel 23 so that liquid from pump 30 may flow through channels 34 and 23, surge valve I0 and channel I2 into cylinder 1 and act upon ram 8. Platen I is then urged downward by pump pressure acting upon the combined areas of ram 6 and pistons 3.

The pressure created by pump 30 in each direction of delivery is limited by two resistance valves 88 and 89 which are ordinarily built into the pump casing but which, for the purpose of illustration, have been shown as having the inlets thereof connected, respectively, to channels 34 and 35 and the outlets thereof connected to an overflow pipe 90 which limits the level of the liquid in surge tank 8 and discharges into reservoir 4|.

When the pressing operation has been com-' pleted, control lever 59 is swung to the position shown in Fig. 7, thereby'openin-g groove 56 to port 58 so that gear pump liquid acting upon pisblock 32 toward the left ends of cylinders 4 to raise pistons 3 and ram 6 but, if it were not for the bypass through valve 45, the pressure prevailing in the upper ends of cylinders 4 and I would hold surge valve I0 closed so that the liquid in the upper end of cylinder 1 would prevent ram 6 from being raised. Also, this high pressure would extend through channels 34, 62 and 10 to the right end of valve cham-' ber 66 and hold valve 61 in the position shown in Fig. 3. Ram 6 would thus -be prevented from being raised until pump 30 .had pumped enough liquid out of cylinder 1 to reduce the pressure therein sufiieiently to permit surge valve In to shift.

Since the oil ordinarily used as the motive liquid is somewhat elastic, the liquid in cylinder 1 would be compressed so much that an appreciable volume would have to be pumped out of cylinder 1 before the pressure therein would be, reduced suificiently to permit surge valve I8 to be shifted.

Consequ'ently,- a considerable delay would ensue before ram 6 started to move upward, and this delay has been found to be equal to as much as 25% of the time required for a complete pressing operation.

However, by providing a bypass through valve 45, a delay in reversing ram 1 is avoided for the reason that, when lever 59 is swung toward the left, passage 85 registers with channel 84 and passage 81 registers with channel 85, as shown in Fig; '7, so that liquid may escape from cylinder 1 through channel 12, surge valve iii, channels 23, 34 and 8|, throttle valve 82, channels 83 and 84, passages 86 and 81, channels 85 and 1'5, chamber 12, channel 13 and resistance valve-14 into reservoir 4i at a rate determined by throttle valve 82 which is so adjusted that ram 6 may be re-,

,surge valve for controllingthe and from said ram versed quickly but not instantaneously as instantaneous reversal would cause sudden expansion of the liquid.

When pump 38 is reversed it delivers liquid into channel 35 and raises the pressure therein. This pressure extends through channels 63 and II to the left end of valve chamber 66 and shifts valve 61 to the position shown in Fig. l: Pressure also extends through channels 21 and- 26 to counterbore l1 and shifts valve member i to the position shown in Fig. 1, liquid being expelled by valve member i5 from the left end of bore H through channel 28, check valve 31 and channel 23 into channel 34.

With valve member l5 in the position shown in Fig. 1,- the liquid discharged by pump 30 flows through channel 35 to the lower ends of cylinders 4 and raises pistons 3 which raise ram 6 and cause it to expel liquid from cylinder 1 through channel i2, bore II and channel 9 into surge tank 8.

Pistons 3 in moving upward expel liquid from cylinders 4 through channel 34 to the intake of pump 30. Since, due to the displacement of piston rods 5, pistons 3 will expel liquid from the upper ends of cylinders 4 at a rate greater than the rate at which pump 30 delivers liquid to the lower ends thereof, the excess liquid will be exhausted through channel 62, chambers 66 and 12, channel 13 and resistance va1ve'14 into reservoir 4|.

When platen l approachesthe upper limit of its movement, lever 59 is operatedto cause the displacement of pump 30 to be reduced to zero to thereby bring the press to rest.

The hydraulic press herein described is susceptible of various modifications without departing from the scope of the invention as hereafter claimed.

The invention is hereby claimed as follows: 1. A hydraulic speed press, comprising a movable member for exerting a force upon a station:-

ary object, a reciprocating hydraulic motor for" advancing said member into engagement with said object and for retracting it therefrom, a ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven reversible pump for supplying liquid to said motor to cause it to reciprocate said member and, said ram and for supplying liquid to said ram cylinder to create pressure therein,

fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for supplying liquid to said cylinder during advance of said ram and for receiving liquid from said cylinder during retraction of said ram, a flow of liquid to cylinder, said valve being adapted to open said cylinder to said tank and in the other side a shock due to the V close it to said pump in response to the pressure in one side of said circuit exceeding the pressure thereof and to close said cylinder to said tank response to the pressure in said other side ex ceeding a predetermined value, pump control means for causing said pump to deliver liquid in one direction or the other and thereby cause said motor to advance or retract said member, said control means including an elementmovable'in one direction to effect an advance of said member and movable in the opposite direction to effect a retraction of said member, and means responsive to the movement of said element a given distance in said opposite direction for relieving the pressure in said ram cylinder.

2. A hydraulic speed press, comprising a movable member forexerting a force upon a stationary object, a reciprocating hydraulic motor for advancing said member into engagement with said object and for retracting it therefrom, a ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven reversible pump for supplying liquid to said motor to cause it to reciprocate said member and said ram and for supplying liquid to said ram cylinder to create pressure therein, fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having. pressure and return sides, a surge tank for supplying liquid to said cylinder during advance of said ram and for receiving liquid from said cylinder during retraction of said ram, a surge valve for controlling the flow of liquid to and.

from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said tank and open it to said pump in response to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to deliver liquid in one direc-.-

tion or the other and thereby cause said motor to advance or retract said member, said control means including an element movable in one direction to effect an advance of said member and movable in the opposite direction to effect a retraction of said member, means responsive to the movement of said element a given distance in said opposite direction for relieving the pressure in said ram cylinder, and means for limiting the rate at which the pressure in said ram 7 cylinder is relieved.

3. A hydraulic speed press, comprising a movable member for exerting a force upon a stationary object, a reciprocating hydraulic motor for advancing said member into engagement with said object and for retracting it therefrom, a ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven reversible pump for supplying liquid to said motor to cause it to reciprocate said member and said ram and for supplying liquid to said ram cylinder to create pressure therein, fluid and open it to said pump in I channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for supplying liquid to said cylinder during advance of said ram and for receiving liquid. from said cylinder during retraction of said ram, a surge valve for controlling the flow of liquid to and from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said tank and open it to saidpump in response to the pressure in said other side exceeding a 5 predetermined value, pump control means for causing said pump to deliver liquid in one direction or the other and thereby cause said motor to advance or retract said member, said control means including a control valve movable in one 10 direction to effect an advance of said member and movable in the opposite direction to effect a retraction of said member, and means including a relief channel for connecting said control valve to said ram cylinder, said control valve 1| having a bypass passage formed therein and so arranged as to connect said relief channel to an exhaust upon said control valve being moved in said opposite direction to a predetermined position to thereby relieve the pressure in said ram 20 cylinder.

4. A hydraulic speed press, comprising a movable member for exerting a force upon a stationary object, a reciprocating hydraulic motor for advancing said member into engagement with 85 said object and for retracting it therefrom, a ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven reversible pump for supplying liquid to said motor to cause it to reciprocate said mem- 80 her and said ram and for supplying liquid to said ram cylinder to create pressure therein, fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for 86 supplying liquid to said cylinder during advance of said ram and for receiving liquid from said cylinder during retraction of said ram, a surge valve for controlling the flow of liquid to and from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said tank and open it to said pump in response 45 to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to deliver liquid in one direction or the other and thereby cause said motor to advance or retract said member, said control 60 means including a control valve movable in one direction to effect an advance of said member and movable in the opposite direction to efiect a retraction of said member, means including a relief channel for connecting said control valve 55 to said ram cylinder, said control valve having a bypass passage formed therein and so arranged as to connect said relief channel to an exhaust upon said control valve being moved in said opposite direction to a predetermined position to thereby relieve the pressure in said ram cylinder,

and a throttle valve for controlliiig the rate of flow through said relief channel to thereby control the rate at which the pressure in said'ram cylinder is relieved.

5. A hydraulic press of the downward pressure type, comprising a movable member for exerti-nga force upon a stationary object, a difl'erential hydraulic motor for advancing said member downward into contact with said object and for 10 retracting it out of contact therewith, a vertical ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven pump for supplying liquid to said cylinder to create pressure therein and for delivering liquid in one direction or the other to said motor vto cause it to move said member in one direction or the other, fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for supplying liquid to said cylinder during downward movement of said ram and for receiving liquid from said cylinder during upward movement of said ram, a surge valve for controlling the flow of liquid to and from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to. said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said tank and open it to said pump in response to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to deliver liquid in one direction or the other and thereby cause said motor to move said ram vertically in one direction or the other, a source of liquid, a valve chamber connected to said source, fluid channels connecting said source to opposite sides of said circuit, and an automatic valve arranged in said chamber and operable by the difference in pressure prevailing in oppositesides of said circuit to connect said source to the low pressure side of said circuit and close it to the high pressure side of said circuit in each direction of pump delivery to thereby compensate for the difference between the volume of liquid discharged by said pump and the volume returned thereto from said circuit, and also to close said return side to said source in response to said member descending by gravity to thereby cause the outflow from said motor to be metered by said pump and said member permitted to descend only at the rate determined by the adjustment of said pump.

6. A hydraulic press of the downward pressure type, comprising a movable member for exerting a force upon a stationary object, a differential hydraulic motor for advancing said member downward into contact with said object and for retracting it out of contact therewith, a vertical ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven pump for supplying liquid to said cylinder to create pressure therein and for delivering liquid in one direction or the other to said motor to cause it to move said member in one direction or the other, fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for supplying liquid to said cylinder during downward movement of said ram and for receiving liquid from said cylinder during upward movement of said ram, a surge valve for controlling the flow ofv liquid to and from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said-z tank and open it to said pump -in response to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to deliver liquid in one direction or the other and thereby cause said motor to move said ram vertically in one direction or the other, a source ofliquid, a valve chamber connected to said source, fluid channels connecting said source to opposite sides of said circuit, an automatic valve arranged in said chamber and operable by the difference in pressure prevailing in opposite sides of said circuit to connect said source to the low pressure side of said circuit and close it to the high pressure side of said circuit in each direction of pump delivery to thereby compensate for difference between the volume or liquid discharged returned thereto" from said circuit, and also to close said return side to said source in response to said member descending by gravity to thereby cause the outflow from said motor to be metered by said pump and said member permitted to descend only at the rate determined by the adjustment of said pump, a control element included in said control means and movable in one direction to efiect a downward movement of said member and movable in the opposite direction to effect an upward means responsive to the movement of said element in said opposite direction to a given position for relieving the pressure in said cylinder and in the channels communicating therewith to thereby permit said surge valve and said automatic valve to shift promptly upon said element, being moved to said position, and means for limiting the rate at which the pressure in said ram cylinder is relieved.

7. A hydraulic press of the downward pressure type, comprising a movable member for exerting a force upon a stationary object, a differential hydraulic motor for advancing said member downward into contact with said object and for retracting it out oi contact therewith, a vertical ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven pump for supplying liquid to said cylinder to create pressure therein and for delivering liquid in one direction or the other to said motor to cause it to move said member in one direction or to the other, fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for supplying liquid to said cylinder during downward movement of said ram and for receiving liquid from said cylinder during upward movement of said ram, a surge valve for controlling the flow of liquidto and from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to said pump in response to the pressure in one side of said circuit exceeding the pressure inthe other side thereof and to close said cylinder to said tank and open it to said pump in response to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to deliver liquid in one and thereby cause said motor to 'move said ram vertica y in one direction or the other, a source of liquid, a valve chamber connected to said source, fluid channels connecting said source to opposite sides of said circuit, an automatic valve arranged in said chamber and operable by the difference in pressure prevailing in opposite sides of said circuit to connect said source to the low pressure side of said circuit and close it to the high pressure side of said circuit in each direction of pump delivery to thereby compensate for the difference between the volume of liquid discharged by said pump and the volume returned thereto from said circuit, and also to closesaid return side to said source in response to said member descending by gravity to --thereby cause the outflow from said motor to be metered by said pump andsaid member permitted to descend only at the rate determined by the adjustment of saidpump, a control element included in said control means and movable in one direction to by said pump and the volume permit said surge valve movement of said member,

direction or the other,

effect a downward movement of said member and movable in the opposite direction to effect an upward movement of said member, and means responsive to the movement of said element-in said opposite direction to a given position for relieving the pressure in said cylinder and in the channels communicating therewith to thereby to shift promptly upon said element being moved to said position.

8. A hydraulic press of the downward pressure type, comprising a movable member for exerting a force upon a stationary object, a differential hydraulic motor for advancing said member downward into contact 'withsaid object and for retracting it out of contact therewith, a vertical ram cylinder, a ram fitted in said cylinder and connected to said member to move therewith, a power driven pump for supplying liquid to said cylinder to create pressure therein and for delivering liquid in one direction or the other to said motor to cause it to move said member in one direction or the other, fluid channels connecting said pump and said motor and forming therewith a hydraulic circuit having pressure and re 'turn sides, a surge tank for supplying liquid to said cylinder during downward movement of said ram and for receiving liquid from said cylinder during upward movement of said ram, a surge valve for controlling the flow of liquid to and from said ram cylinder, said valve being adapted to open said cylinder to said tank and closeit to said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said tank and open it to said pump in response to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to. deliver liquid in one direction or the other and thereby cause said motor to move said ram vertically in one direction or the other, a source of liquid, a valve chamber connected to said source, fluid channels connecting said source to opposite sides of said circuit, an automatic valve arranged in said chamber and operable by the difierence in pressure prevailing and said automatic valve in opposite sides-of said circuit to connect said ber permitted to descend only at the rate determined by the adjustment of said pump a control valve included in said control means and movable in one direction to effect a downward movement of said member and movable in the opposite direction to effect an upward movement of said member, means including a relief channel for connecting said control valve to said'ram cylinder, said control valve having a bypass passage formed therein and so arranged as to connect said relief channel to an exhaust upon said control valve being moved in said opposite tion to a predetermined position to thereby relieve the pressure in said ram cylinder and per-- mit said surge valve and said automatic valve to shift promptly upon said valve being moved to said positon.

9. A hydraulic press of the downward pressure directype, comprisinga movable member for exerting a force upon a stationary object, a difierential hydraulic motor for advancing said member downward into contact with said object and for retracting it out of contact therewith, a vertical ram cylinder, a ram fitted in said cylinder and connected to saidmember to move therewith, a power driven pumpfor supplying liquid to said cylinder to create pressure therein and for delivering liquid in one direction or the other to said motor to cause it to move said member in one direction or the other, fluid channelsconnecting said pump and said motor and forming therewith a hydraulic circuit having pressure and return sides, a surge tank for supply liquid to said cylinder during downward movement of said ram and for receiving liquid from said cylinder during upward movement of said ram, a surge valve for controlling the flow of liquid to and from said ram cylinder, said valve being adapted to open said cylinder to said tank and close it to said pump in response to the pressure in one side of said circuit exceeding the pressure in the other side thereof and to close said cylinder to said tank and open it to said pump in response to the pressure in said other side exceeding a predetermined value, pump control means for causing said pump to deliver liquid in one direction or the other and thereby cause said motor to move said ram vertically in one direction or the other, a source of liquid, a valve chamber connected to said source, fluid channels connecting said source to opposite sides of said circuit, an automatic valve arranged in said chamber and operable by the difference in pressure prevailing in opposite sides of said cir-' cuit to connect said source to the low pressureber permitted to descend only at the rate deter-' mined by the adjustment of said pump, a control valve included in said control means and movable in one direction to effect a downward movement of said member and movable in the opposite direction to effect an upward movement of said member, means including a relief channel for connecting said control valve to said ram cylinder, said control valve having a bypass passage formed therein and so arranged as to connect said relief channel to an exhaust upon said control valve being moved in said opposite direction to a predetermined position to thereby relieve the pressure in said ram cylinder and permit said surge valve and said automatic valve to shift promptly upon said valve being moved to said position, and a throttle valve for controlling the rate of flow through said relief channel to thereby control the rate at which the pressure in said ram cylinder is relieved.

RANSOM TYLER. 

